HelpPC 2.10 Quick Reference Utility Copyright 1991 David Jurgens

        INT 21,37 - Get/Set Switch Character (Undocumented, DOS 2.0+)

       AH = 37h
       AL = 0  get switch character into DL;  some systems return "-"
          = 1  set switch character to value in DL
          = 2  read device prefix flag into DL;  returns DL = 0 indicating
               devices must be accessed using /DEV/device. A non-zero value
               indicates devices may be accessed without prefix
          = 3  set device prefix flag, device names must begin with \DEV\.
       DL = new switch character (AL=1)
          = 00  \DEV\ must preceed device names (AL=3)
          = 01  \DEV\ is not neccesary in device names (AL=3)

       on return:
       AL = FF  illegal subfunction code specified
       DL = current switch character (AL=0)
          = device availability (AL=2, always FF with DOS 4.x+)

       - subfunctions 0 and 1 were formerly available as a CONFIG.SYS
         command in DOS versions before 3.x;   also supportedin the OS/2
         compatibility box
       - subfunctions 2 and 3 were available in DOS 2.x only;  they have
         no effect in DOS 4.x+
       - /DEV/ prefix is valid in DOS 2.x by default, setting the flag makes
         it mandatory.  DOS internal commands like DIR, TYPE and DEL do not
         recognize filenames the are identical to device names regardless of
         the setting of the AVAILDEV flag.

Esc or Alt-X to exit int 21,37 Home/PgUp/PgDn/End ←↑↓→
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